Rock duster



July 13, 1965 G. D. GURNEY 3,194,443

ROCK DUSTER Filed July 1, 1963 5 Sheets-Sheet 1 AfrroRNEYs INVENTORGlemumey BY VWM G. D. GURNEY ROCK DUSTER 5 Sheets-Sheet 2 Filed July 1,1963 mw Illnw ma /w F H ON. H I .l: p m mw S. O

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ATTORNEYS July 13, 1965 Filed `Ju1y"1, 196s G. D. GURNEY ROCK DUSTER 5Sheets-Sheet 5 INVENTOR.

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ATTORNEYS United States Patent O 3,194,443 ROCK DUSTER Glenn D. Gurney,Canton, Ohio, assigner to The American Mine Door Company, Canton, Ohio,a corporation of Ohio Filed July 1, 1963, Ser. No. 292,017 2t) Claims.(Cl. Z22- 193) The invention relates to apparatus for spreading rockdust in coal mine tunnels and the like, for covering and mixing with thecoal dust on the walls, ceilings, and iloors, and more particularly toan apparatus of this general type having novel conveying means as welllas novel spreading means for the rock dust.

It is common practice to spray the interiors of coal mine tunnels andsimilar places with rock dust in order to prevent explosion of the coaldust 4which accumulates on the oor, walls and ceilings thereof.

The apparatus generally used for this purpose comprises a vehicle whichmay be 'arranged to be propelled upon the railroad rails in the mines orotherwise, such vehicle having a hopper containing a supply of rockdust. Screw means is usually provided for feeding the -rock dust Ifromt-he hopper to a feed tube or pipe through which an air blast is passed-for spraying the rock dust from a nozzle connected to the feed tube.

In Ithe past, di'iculty has been experienced by the rock dust having atendency to pack and arch over the feed screw and pack in the ffeedtube, so that yfeeding of the rock dust to the nozzle is interrupted,requiring stopping of the operation to break up the packed or caked rockdust.

Furthermore, this feeding of the rock dust from the hopper to the feedtube, by a feed screw, and then spraying it through the nozzle was aslow operation.

The object of Ithe present invention is to provide a rock dustingapparatus which overcomes the above diticulties and disadvantages, andwhich will quickly and easily convey the rock dust to the spreadingmeans and rapidly spread it upon the walls, ceilings and floors of minetunnels and similar pl-aces.

Another object -of the invention is to provide rock dusting apparatushaving simple, effective and inexpensive means for rapidly and uniformlyconveying the rock dust without any danger of packing or caking.

A further object of the invention is to provide apparatus of thecharacter referred to having conveying means of the general typedisclosed in Ihlefeldt Patent No. 1,971,853, dated August 28, 1934, inwhich a conveying trough has a porous bottom wall through which air orgas under pressure is forced to maintain the pulverulent material beingconveyed in a suspended state approximating a fluid condition.

A still further object of the invention is to provide rock dustingapparatus of this character comprising a hopper or bin for containingrock dust, the bottom wall of the hopper or bin being in the form of aporous flexible member inclined slightly downward toward the dischargeend.

Another object of the invent-ion is to provide such a rock dustingapparatus in which fan air-tight chamber is located lbeneath t-he hopperor bin, the porous flexible member forming the top W-all of theair-tight chamber, means being provided for admitting a gaseous mediumunder pressure to said Iair-tight chamber at spaced points v throughoutthe length thereof.

A still further object of the invention is to provide a rock duster of-this general type in -which the rock dust is discharged from two spacedoutlets in the end wall of the hopper or b-in, directly into twopreferably oppositely rotating fans which spread the rock dust evenlyover the Vehicle.

surfaces of the ceiling, side walls and tioor of a tunnel or similarplace in a coal mine.

The .above and other objects, apparent from the drawings and followingdescription, may be atta-ined, the above `described diiiicultiesovercome `and the advantages and results obtained, by the apparatus,construction, arrangements and combinaitons, sub-combinations and partswhich comprise the present invention, a preferred embodiment of which,illustrative of the best mode in which applicant has contemplatedapplying the principle, being set forth in detail in the followingdescription and illustrated in the accompanying drawings.

In general terms the invention may be briefly described as comprising anelongated hopper or bin having an open top7 substantially vertical rsidewalls and end walls, and a ilexible porous bottom wall, slightlyinclined from one end wall to the other.

An air-tight chamber is located directly below and coextensive with theinclined bottom wall, which 4forms the top wall of said air-tightchamber. Means, such as lan air pump, is provided for furnishing air orother gaseous medium, and discharge pipes from thepump communicate atspaced inter-vals with said `air chamber so as to maintain a uniformpressure throughout the air chamber.

A V-shape divider is preferably located in the discharge end of thehopper or bin, dividing the same into two diverging legs, there being adischarge slot in the adjacent end wall at the terminal end of each leg.

A motor is mounted beyond the other end of the hopper or bin andoperatively connected, as by sprocket wheels and chain, w-ith the airpump for driving the same. A main drive shaft is located centrally belowthe a-ir cham- -ber and also connected by sprocket wheels and chain withthe motor.

A spaced pair of transversely disposed plates are located yforwardlyfrom the discharge end of the hopper or b-in and extend entirely acrossthe discharge end thereof. Between these transverse plates are locatedfans, one near each end of the plates.

Each fan is 4centered relative to one of the discharge outlet slots inthe adjacent end wall of the hopper or bin. An opening is formed in thefirst of the two plates, concentric with each fan, and a U-shape troughextends between each discharge outlet slot and the correspondingopening.

One lof the fans is connected directly to the main drive shaft, as bysprocket wheel and chain drive, and the other =fan is connected to thedrive shaft through a reversing gear, so that the fans rotate inopposite directions.

Having thus briefly described the invention, reference is now made tothe accompanying drawings illustrating a perferred embodiment of theinvention, in which;

FIGS. la and 1b are a plan view of the new rock duster apparatus, withparts broken away for the purpose of illustration;

FIGS. 2a and 2b are a side elevation with parts broken away;

FIG. 3 is an elevation of one end of the apparatus, showing the motor,and the starter box;

FIG. 4 is an elevation of the opposite end of the apparatus, showing thefans;

FIG. 5 is a section on the line 5 5, FIG. 1b; and

FIG. 6 is a section on the line 6 6, FIG. 5.

The apparatus is designed to be moved through mine tunnels and the like,and is adapted to be mounted on a vehicle which may be arranged to beconveyed upon a railroad track by means of a locomotive or otherwise.The vehicle is not illustrated as it in itself forms no part of theinvention. l

The apparatus comprises a rectangular frame, indicated generally at 1,adapted to be mounted upon the This frame includes longitudinallydisposed angle members 2, joined at their rear ends by a transverselydisposed angle member 3, and at their forward ends by the transverselydisposed plate 4, to which the vertical angle members are also attached.

' Vertical angle members 6'are connected to therear transverse member 3and at their upper ends are connected by a transverse angle member 7. Apair of vertical angle members 8 are mounted upon the longitudinalmembers 2, at points spaced forwardly from the rear end of theapparatus, and a transversely disposed plate 9 is connected at oppositeends to the upper portions there- Atransversely disposed angle member 1@is connected to the upper edge of the transverse plate 9. Longitudinallydisposed angle members 11 are located between opposite ends of thetransversely disposed angle members 7 and 10, and a centrally locatedangle member 11a is located between the central portions of thetransverse angle members 7 and 10, forming a support for a cover plate12 for the rear portion of the frame.

A spaced pair of transversely disposed angle members 13 are mounted atopposite ends upon the longitudinally disposed frame members 2, at apoint spaced forwardly from the rear transverse angle member 3, andprovide a support for the motor 14, the flanged feet 15 of which aremounted upon angle members 13 and connected thereto by bolts 16.

Spaced, transversely disposed angle members 17 and ISvare locatedforwardly of the angle members 13 and connected at their opposite endsto the longitudinal angle members 2. A short angle Vmember 19 is mountedupon one end portion of the member 17.

An air'pump 2t) is provided with anged feet-21 connected to the anglemembers 13 and 19 by bolts 22. Sprocket wheels 23, upon the shaft 24 ofthe motor 14, are connected by chains 25 with sprocket wheels 2.6 uponthe main drive shaft 27 which is longitudinally centrally locatedthrough the frame.

The shaft 27 is journalled in a bearing 28 mounted upon the transverselydisposed angle member 17 and in bearings 29 and 30 mounted upon thetransversely disposed angle members 31 and 32. Bolts 33 and 34 attach gthe bearings 29 and 30 to the angle members 31 and 32.

A sprocket wheel 35, upon the shaft 27, is connected by chain 36 withsprocket wheel 37 upontheshaft 3S 'of the air pump 20. A hopper,indicated generally at 39, is formed within the frame 1 between thetransverse walls 4 and 9 which form the front and rear end walls for thehopper, the longitudinal Vside walls of which are shown at 40.

The bottom wall of the hopper is slightly inclined orwardly anddownwardly from the rear wall 9 toward the front wall 4. This bottomwall 41 is porous and preferably flexible and, as best shown in FIGS. 5and 6, is preferably formed of several layers of canvas supported by aheavy wire mesh 42 which is supported upon the transverse angle members43. The longitudinal edges of the canvas 41 are turned up against theside walls 4t) and are clamped thereagainst by the longitudinal bars 41aand bolts 41b. Y n

A gas chamber 44 is located below the hopper and, coextensive therewith.The front and rear end plates 4 and 9 respectively form the front andend Walls of the gas chamber and the lower portions 45 of the side walls41B form the side walls thereof.

The lower terminal edge of the side walls 40 are turned inwardly asshown at 46 in FlG.- 5 and the bottom wall 47 of the gas chamber isattached thereto and supported on the transverse angle members 46.

Air or other suitable gaseous medium under pressure is discharged fromthe airpump 20 through then pipe 50 which is-connected to the twolongitudinally disposed pipes 51 located beneath the gas chamber 44 nearopposite sides thereof and kconnected at spaced intervals to the gasYchamber as indicated at 52.

A V-shape or triangular divider 53 may be Vlocated in the forward endvof the hopper dividing this end of the hopper into two diverging legsindicated at 54and 55 in FIG. lb, A discharge outlet slot 56 is formedinthe end wall 4 at the end of eachrleg 54 or 55 and at the oor levelthereof as shown in FIGS. 5 and 6.

Longitudinally diagonally disposed angle members 57 are located upon thebottom wall 47, directly below the bottom edges of the V-shape dividerV53, as best shown in FIGS. 1b and 5. The inner edges of the canvas 41,and wire mesh 42, are located upon the corresponding angle members 57and clamped thereupon by bolts SS located through the horizontal flangesV59 at the lower edges of the V-shape divider 53 and through the anglemembers 57. Y

Y The endl of the canvas-41 is located through the correspondingdischarge outlet slot 56 and extends downalong the front face of the endplate 4 as indicated at 60. Each end portion 60 of the canvas is clampedagainst the front face of the end plate 4 by the corresponding bearingblock 61 and bolts 62 (FIGS. 1b and 6).

Two vertically aligned transversely disposed plates 63- 63 are locatedin front of the end plate 4 and spaced therefrom, and the transverselydisposed plate 64 is spaced forwardly from the plates 63-63.

A pair of similar fans 65-65' are provided. The fari 65 is locatedbetween the plates 63 and 64 and the fan 65 is located between theplates '63 and 64. The shaft 66 of fan 65 and the shaft S1 of fan65Yeach has one end journalled in a bearing 67, which may be a rollerbearing or ball bearing, located in a bearing block 61.V The other endof the shaft 66 of the fan 65 is journalled in a bearing 68, mountedupon an angle member 69 carried by the plate 64.

A sprocket wheel 7@ is fixed upon the forward end of the shaft 66 of thefan 65and connected by chain 71 with sprocket wheel 72 upon the forwardend ofV the main shaft 27, which is journalled in a-bearing'73, mountedupon a bracket 74, carried by the angle member 69.

The reversing gear box 75 isVm-ounted upon a bracket 76 carried by thetransverse plate 64. A sprocket wheel 77, upon the shaft 7S of thereversing gear, is connected by chain 79 with sprocket wheel 8i) uponthe main drive shaft 27. The shaft S1, of the fan 65, is connectedwithin the reversing gear box 75,.the other end thereofbeing journalledin a bearing 67 located within the corresponding bearing box 61.

Each plate 63 and 63Yhas an opening S2 therein concentric with thecorresponding fan shaft 66 and 81. A substantially channel-shape trough83 is located in front of each outlet slot 56, being mounted upon thecorrespending bearing block 61, and extends to a point adjacent thecorresponding opening 82 in the transverse piate 63 or 63 as the casemay be.

T he plates 63, 63 and 64 are supported from the front end plate 4 bymeans of the double partition indicated generally at 84. T his partitionis located between the fans 65 and 65 and comprises the two parallelvertical portions 235 connected at their upper ends as at 36, eachvertical portion 85 merging intopa downwardly curved portion 7 whichterminates below the outer side of the adjacent fan with forward andrearward cutouts 3S and S9 and reduced terminal portion 9d therebetween.i

The double partition above described is welded to the end plate 4 at itsinner edge as indicated at 91 and welded to the outer `transverse platey64 at its outer edge as at 92.* The inner transverse plates 63 and 63'are shaped to fit theV contours of the two vertical portions 8,5 andcurved portions S7 of the double partition.

An angle member 93- is attached to the upper edges of the innertransverse plates 63 Vand 63 and to angle members 94 connected Yto theforward side of the end plate 4. Y

ln the Voperation of the apparatus, the hopper is filled with rockY dustand the vehicle carrying the apparatus is conveyed to the locationwithin a mine tunnel to be dusted. The motor 14 is then started:operating the shaft 27 through the sprocket gearing 23-25-26.

The air pump is thus operated through the sprocket and chain gearing35-36-37 and the fans 65 and 65 are rotated in opposite directions bythe sprocket and chain gearing 70-71-72, sprocket and chain gearing78-79-3@ and reversing gear 7S.

Air under pressure is discharged from the pump 20, through the pipe Siland tubes 51 and into the air chamber 44, at spaced pointsthr-oughout'its length, through the connections 52. The air underpressure is forced upwardly from the air chamber, through the porousbottom wall 41, maintaining the rock dust in such condition that itassumes the characteristics of a fluid emulsion.

The air under pressure passing up through the porous bottom wall 41passes upward through the rock dust, separating each particle of rockdust from the other particles thereof.

The rock dust in this condition will be conveyed forwardly upon theporous bottom wall, being diverted by the triangular separator 53 intothe two legs 54 and 55 of the hopper and discharged through thedischarge outlet slots 56 and through the channel-shaped troughs 83 andthe openings 82, into the rapidly rotating fans 65 and 65', which throwthe rock dust upwardly and outwardly in opposite directions, uniformlycoating the ceiling and side walls of the mine tunnel with rock dust, asucient number of the rock dust descending to the oor of the mine so asto adequately cover, or mix with, the coal dust thereon.

From the above it will be evident that a simple, etlicient and easilyoperated apparatus is provided for rapidly and uniformly dusting theside walls, ceiling and floor of a mine tunnel or the like, without thediflicult-ies and disadvantages of present rock dusting apparatus.

In the foregoing description certain terms have been used for brevity,clearness and understanding, but no unnecessary limitations are to be-implied therefrom beyond the requirements of the prior art, becausesuch words are used for descriptive purposes herein and are intended tobe broadly construed.

Moreover, the embodiments of the improved construction illustrated anddescribed herein are by way of eX- ample, and the scope of the presentlinvention is not limited to the exact details of construction.

Having now described the invention or discovery, the construction, theoperation, and use of preferred embodiments thereof, and the advantagesnew and useful results obtained thereby; the new and usefulconstruction, and reasonable mechanical equivalents thereof obvious tothose skilled in the art, are set forth in the appended claims.

I claim:

1. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlets in one endwall, a gas chamber below and coextensive with the bottom wall, meansfor introducing a gaseous medium under pressure into said gas chamber, atransversely disposed rotary fan located in front of each dischargeoutlet, spaced transverse walls between which the `fans are located, thespace between said transverse walls being unobstructed above each fanand at opposite ends of said transverse walls, there being openingsconcentric with the fans in the innermost transverse wall, and means forrotating the fans, whereby rock dust will be conveyed along said porousbottom wall and through said discharge outlets and drawn into said fansand will be blown upwardly and outwardly thereby from between saidtransverse walls.

2. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being yspaced discharge outlets in one endwall, a gas chamber below and coextensivel with the bottom wall, meansfor introducing a gaseous medium under pressure into said gas chamber, atransversely disposed rotary fan located in front of each dischargeoutlet, spaced transverse walls between which the fans are located, thespace between said transverse walls being unobstructed above each fanand at opposite ends of said transverse walls, there being openingsconcentric with the fans in the innermost transverse wall, and means forrotating the fans in opposite directions with the upper sides of thefans rotating toward each other, whereby rock dust will be conveyedalong said porous bottom wall and through said discharge outlets anddrawn into said fans and will be blown upwardly and outwardly therebyfrom between said transverse Walls.

3. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlets in one endwall, a gas chamber below and coextensive with the ybottom wall, meansfor introducing a gaseous medium under pressure into said gas chamber, atransversely disposed rotary fan located in front of each dischargeoutlet, spaced transverse walls between which the fans are located, thespace between said transverse walls being unobstructed above each fanand at opposite ends of said transverse walls, there being openingsconcentric with the fans in the innermost transverse wall, saidinnermost transverse wall being spaced from said one end wall, asubstantially channelshape trough between each disch-arge outlet and thecorrespending concentric opening, and means for rotating the fans,whereby rock dust will be conveyed along said porous bottom wall andthrough said discharge outlets into said channel-shape troughs and drawnfrom said troughs into said fans and will be blown upwardly andoutwardly thereby from between said transverse walls.

4. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlets in one endwall, a gas chamber below and coextensive with the bottom wall, meansfor introducing a gaseous medium under pressure into said gas Chamber, atransversely disposed rotary fan located in front of each dischargeoutlet, spaced transverse walls between which the fans are located, thespace between said transverse walls being unobstructed above each fanand at opposite ends of said transverse walls, there being openingsconcentric with the fans in the innermost transverse wall, a verticalpartition between said transverse walls on the inner side of each fan,each of said partitions merging into an outwardly curved portionterminating beneath the corresponding fan, and means for rotating thefans, whereby rock dust will be conveyed along said porous bottom walland through said discharge outlets and drawn into said fans and will beblown upwardly and outwardly thereby from between said transverse walls.

5. A rock duster comprising a hopper having side walls, end walls, and aforwardly and downwardly inclined porous bottom wall, there being spaceddischarge outlets in the forward end wall, a gas chamber below andcoextensive with the bottom wall, means for introducing a gaseous mediumunder pressure into said gas chamber, a transversely disposed rotary fanlocated in front of each discharge outlet, spaced transverse wallsbetween which the fans are located, the space between said transversewalls being unobstructed above each fan and at opposite ends yof saidtransverse walls, there being openings concentric with the fans in theinnermost transverse wall, and means for rotating the fans, whereby rockdust will be conveyed along said porous bottom wall and through saiddischarge outlets and drawn into said fans and will be blown upwardlyand outwardly thereby from between said transveise walls.

6. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlets in one endwall, a gas chamber below and coextensive with the bottom wall, meansfor introducing a gaseous medium under pressure into said gas chamber,aftransversely disposed rotary fan located in disease 7 front of eachdischarge outlet, spaced transverse, walls between which the fans arelocated, the space between said transverse walls being unobstructedabove each fan and at opposite ends of said transverse walls, therebeing openings concentric with the fans in the innermost transversewall, a vertical partition between said transverseV walls on the innerside of each fan, each of said partitions merging into an outwardlycurved portion terminating beneath the corresponding fan in a reducedterminal portion, and means for rotating the fans, whereby rock dustwill be conveyed along said porous bottom wall and through saiddischarge outlets and drawn into said fans and will be blown upwardlyand outwardly thereby from between said transverse walls.

7. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlet in one end wall,`a gaschamber below and coe'xtensive with the bottom wall, means forintroducing a gaseous medium under pressure into said gas chamber, atransversely disposed rotary fan located in front of each dischargeoutlet, spaced transverse walls between which the fans are located, thespace between said transverse walls being unobstructed above each fanand at opposite ends of said transverse walls, there being openingsconcentric with the fans in the innermost transverse Wall, a verticalpartition between said transverse walls on the inner side of each fan,each of said partitions merging into an outwardly curved portionterminating beneath the corresponding fan, means joining the upper endsof said vertical partitions, and means for rotating the fans, wherebyrock dust will be conveyed along said porous bottom wall and throughsaid discharge outlets and drawn into said fans and will be blownupwardly and outwardly thereby from between said transverse walls.

8. A rock duster comprising a hopper having side walls, end walls, and aflexible porous bottom wall, there being spaced discharge outlets in oneend wall, a gas chamber below and coextensive with the bottom wall,means for introducing Va gaseous medium under pressure into said gaschamber, a transversely Vdisposed rotary fan located in front of eachdischarge outlet, spaced transverse walls between which the fans arelocated, the space between said transverse walls being unobstructedabove each fan and at opposite ends of said transverse walls, therebeing s Vopenings concentric with the fans in the'innermost transversewall, and means for rotating the fans in opposite directions, wherebyrock dust will be conveyed along said porous bottom wall and throughsaid discharge outlets and drawn into said fans and will be blownupwardly and outwardly thereby from between said transverse walls.

9. A rock duster comprising a hopper having side walls, end walls, and aforwardly and downwardly inclined flexible, porous bottom wall, therebeing spaced discharge outlets in the forward end wall, a gas chamberbelow and coextensive with the bottom wall, means for introducing agaseous medium under pressure into said gas chamber, a transverselydisposed rotary fan located in front of each discharge outlet, spacedtransverse walls between which the fans are located, the space betweensaid transverse walls being unobstructed above each fan and at oppositeends of said transverse walls, there being openings concentric with thefans in the innermost transverse wall, and means for rotating the fansin opposite directions, whereby rock dust will be conveyed along saidporous bottom wall and through said discharge outlets and drawn intosaid fans and will be blown upwardly and outwardly therebyrfrom betweensaid transverse walls.

10. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlets in one endwall, a gas chamber below and coextensive with the bottom wall, an airpump, tubes communicating with the discharge side of the air vpump 'andconnected to said gas chamber, a transversely disposed rotary fanlocated in front of each discharge outlet, spaced transverse wallsbetween which the fans are located, the space between said transversewalls being unobstructed above each fan l,and at opposite ends of saidtransverse walls, there being openings concentric with the fans in theinnermost transverse wa1l,fa motor, a'drive shatt operatively connectedto said motor, means operatively connecting the air pump to the driveshaft, and means operatively connecting the fans torthezdrive shaft forrotating the fans, whereby rock dust willbe conveyed along said porousbottom wall and through said discharge outlets and drawn into said fansand will be blown upwardly and outwardly thereby from between saidtransverse walls.

ill. A rock duster comprising a hopper having side walls, end walls andaV por-ous bottom wall, there being spaced discharge outlets in one endwall, a Vgas chamber below and coextensive with the bottom wall, anfairpump, tubes communicating with the discharge side of the air pump andconnected to said gas chamber, a transversely disposed rotary fanlocated in front of each dischargeoutlet, spaced transverse wallsbetween which the fans are located, the space between said transversewalls being unobstructed above each fan and at opposite ends of saidtransverse walls, there being openings concentric with the fans in theinnermost transverse wall, a mot-or, a drive shaft operatively connectedto said motor, means operatively connecting the air pumpto the driveshaft, and means operatively connecting the fans to the drive shaft forrotating the fans in opposite directions, whereby rock dust will beconveyed along said porous bottom wall and through said dischargeoutlets and drawninto said fans and will be blown upwardly and outwardly,thereby from between said transverse walls; v

l2. A rock duster comprising a hopper having side walls, end walls and aporous bottom wall, there being 'spaced discharge outlets in one endwall, a gas chamber below and coextensive with the bottoml wall, an airpump, tubes communicating with the discharge side of the air Vpump andconnected to said gas chamber, a transversely disposed rotary fanlocated in front of each discharge outlet, spaced transversewallsbetween'which the fans are located, the space between said transversewalls being unobstructed above each fan and at opposite ends of saidtransverse walls, there being openings concentric with the fans in theinnermost transverse wall,'a substantially channel-shape trough between'each discharge outlet and the corresponding concentric opening, amotor, a drive shaft operatively connectedto said motor,meansoperatively connecting the air pump to the drive shaft, and meansoperatively connecting the fans to the drive shaft for rotating thefans,whereby rock dust will be conveyed along said porous bottom walland through said discharge outlets into said channel-shape 'troughsV anddrawn from said troughs into said fans'and will be blown upwardly andoutwardly thereby from between said transverse walls. Y

13. A rockduster comprising a hopper having side walls, end walls and aporous bottom wall, there being spaced discharge outlets in theadjacentend wall, a gas chamber below and coextensive with the bottom wall, anair pump, tubes communicating with the discharge side of the air pumpand connected to said gas chamber, a transversely disposedrotary fanlocated' in front of each discharge outlet, spaced transversewallsvbetween which the fans are located, the space .between saidtransverse walls being unobstructed above each fan Yand'at opposite endsof said transverse walls, there being openings concentric with the fansin the innermost transverse wall,v a vertical partition betweensaid'transverse walls on the inner side of each fan, each of saidpartitions merging into an outwardly curvedV portion terminating`beneath the corresponding fan, a motor, a drive shaft operativelyconnected to said motor, means operatively connecting the air pump` tothe drive shaft, and means operatively connecting the fans to thedrive'shaft for rotating the'fans, whereby rock dust willrbe' conveyedalong said porous bottom wall and through said discharge outlets anddrawn into said fans and will be blown upwardly and outwardly therebyfrom between said transverse walls.

14. A rock duster comprising a hopper having Vside walls, end walls, anda forwardly and downwardly inclined porous bottom wall, there beingspaced discharge outlets in the adjacent end wall, a gas chamber belowand coextensive with the bottom wall, an air pump, tubes communicatingwith the discharge side of the air pump and connected to said gaschamber, a transversely disposed rotary fan located in front of eachdischarge outlet, spaced transverse walls between which the fans arelocated, the space between said transverse walls being unobstructedabove each fan and at opposite ends of said transverse walls, therebeing openings concentric with the fans in the innermost transversewall, a motor, a drive shaft operatively connected to said motor, meansoperatively connecting the air pump to the drive shaft, and meansoperatively connecting the fans to the drive shaft for rotating thefans, whereby rock dust will be conveyed along said porous bottom lwalland through said discharge outlets and drawn into said fans and will beblown upwardly and outwardly thereby from between said transverse walls.

1S. A rock duster comprising a hopper having side walls, end walls, anda porous bottom wall, there being spaced discharge outlets in theadjacent end wall, a gas chamber below and coextensive with the bottomwall7 an air pump, tubes communicating with the discharge side of theair pump and connected to said gas chamber, a transversely disposedrotary fan located in front of each discharge outlet, spaced transversewalls between which the fans are located, the space between saidtransverse walls being unobstructed above each fan and at opposite endsof said transverse walls, there being openings concentric with the fansin the innermost transverse wall, a vertical partition between saidtransverse walls on the inner side of each fan, each of said partitionsmerging into an outwardly curved portion terminating beneath thecorresponding fan in spaced cutouts and a reduced terminal portion, amotor, a drive shaft operatively connected to said motor, meansoperatively connecting the air pump to the drive shaft, and meansoperatively connecting the fans to the drive shaft for rotating thefans, whereby rock dust will be conveyed along said porous bottom walland through said discharge outlets and drawn into said fans and will beblown upwardly and outwardly thereby from between said transverse walls.

16. A rock duster comprising a hopper having side Walls, end walls, yanda porous lbottom Wal-l, there being spaced discharge .outlets in theAadjacent end wall, a gas chamber below and coextensive with the b-ottomwall, an air pump, tubes communicating with the discharge side of the.air pump and connected to said gas chamber, a transversely disposedrotary han located in front of each discharge outlet, spaced transversewalls between which the fans are located, the space between saidtransverse walls being unobstructed .above each han and at opposite endsof said transverse walls, there being openings concentric with the fansin spaced cutouts and the innermost transverse wall, a verticalpartition between said transverse walls on the inner sid-e of 'each fan,each of said partitions merging into an outwardly curved portionterminating beneath the corresponding fan in a reduced terminal portion,a motor, a ydrive shaft operatively connected to said motor, meansoperatively connecting the air pump to the drive shaft, and meansoperatively connecting the fans to the drive shaft for rotating the fansin opposite directions, whereby rock dus-t will be conveyed iai-ong saidporous bottom wall and through said discharge outlets and drawn intosaid fans and will be blown upwardly and outwardly thereby from betweensaid transverse Walls.

17. A rock duster comprising a hopper havin-g side walls, end walls anda porous bottom wall, Ithere being spaced discharge outlets in theadjacent end wall, :a gas chamber below and coextensive with the bottomwall, an air pump, tubes communicating with the discharge side of theair pump and connected to said gas chamber, a transversely disposedrotary fan located in front of each discharge outlet, spaced transversewalls between which the -fans are located, the space between saidtransverse walls being unobstructed above each fan .and at opposite endsof said transverse walls, there being openings concentric with the fansin the innermost transverse wall, a vertical partition between saidtransverse walls .on the inner .side of each lfan, each of saidparti-tions merging into an outwardly curved portion terminating beneaththe corresponding fan in spaced cutouts and la reduced terminal portion,means joining the upper `ends of said vertical portions, a motor, adrive shaft operatively connected to said motor, means operativelyconnecting .the Iair pump to the -drive shaft, and means Ioperativelyconnecting the fans to the drive shaft for rotating the fans, wherebyrock dust will be conveyed along said porous bottom wall .and throughsaid `discharge outlets and drawn into said fans and will be blownupwardly and outwardly thereby from between said transverse walls.

i8. A rock duster comprising a hopper having side walls, end walls, anda flexible porous bottom wall, there being spaced discharge outlets inthe adjacent end wall, a gas chamber below fand coextens-ive with thebottom wal-l, and air pump, .tubes communicating with the discharge sideof the air pump `and connected to said gas chamber, la transverselydisposed rotary fan located in front of each discharge outlet, spacedtransverse walls between which the fans are located, the space betweensaid transverse Walls being unobstructed :above cach fan and atVopposite ends of said transverse walls, there being openings concentricwith the fans in the innermost transverse wall, a motor, la :drive shaftoperatively connected to said motor, means operatively connecting theair pump to the drive shaft, and means operatively connecting the fansto the drive shaft for rotating the fans, whereby rock dust will beconveyed along said porous bottom wall and through said -dischargeoutlets and drawn into said fans and will be blown upwardly andoutwardly thereby from between said transverse walls.

19. A rock duster comprising a hopper having side walls, lend walls,`and a forwardly and downwardly inclined, flexible, porous bottom wall,means dividing said hopper into two legs, there being .a dischargeoutlet in the forward end wall at the end of each leg, a gas chamberbelow and coextensive with the bottom wall, an air pump, tubescommunicating with the discharge side of the air pump and connected tosaid gas chamber, a tr|ansversely disposed rotary fan located in frontof each dischange outlet, spaced transverse walls between which the fansare loca-ted, the space between said transverse walls being unobstructedabove each lfan and at opposite ends of .said transverse walls, therebeing openings concentric with the dans in the innermost transversewall, a motor, a drive shaft operatively connected Ito Isaid motor,means opera-tively connecting the air pump .to the drive shaft, andmeans operatively connecting the fans to the drive shaft for rotatingthe fans, whereby rock dust will be conveyed along said porous bottomwall and through said 'discharge outlets and drawn into said fans andwill be blown upwardly and outwardly thereby from between saidtransverse walls.

20. A rock duster comprising a hopper havin-g side Walls, end walls, anda forwardly and downwardly inclined, lflexible, porous 'bottom Wall,means dividing said hopper into two legs, there being a discharge outletin the forward end wall at the end of each leg, la gas chamber below andcoextensive with the bottom wall, an :air pump, tubes communicatingwithV the discharge side of the air pump and connected to said gaschamber, a transversely disposed rotary fan located in lfront vof eachdischarge outlet, spaced transverse wa'lls between wh-ich the lfans arelocated, the space Ibetween said transverse Walls being unobstructedabove each fan `and at opposite ends of said transverse walls, therebeing openings concentric with the fans in the innermost .tnansverseWall, a motor, a `drive shaft operatively connected t-o said moto-r,means operatively connecting the `air pump to the drive shaft, .andmeans `operatively connecting fthe fans to the drive shaft for rotatingthe fans in opposite directions, Whereby rock dust will be conveyedalong said porous bottom Wa=11 .and through said `discharge outletsran-d'drawn into said fans and will be bl-ownuipwardly and outwardlythereby from between said transverse walls.

References Cited by thelxamner UNITED STATES PATENTS,

V1,776,751 9/30v Dim 275- 21 2,645,500 7/53 Moss 275-s X f 2,813,64011/57 Loomis. a02- 29x 3,039,827 6/62 `immistfme er a1. Y3oz-29 XFoREiGN PATENTS 584,809 1/47 Great Britain. 1,121,544 i/62y Germany.

LOUIS J. DnMBo, Primary Examiner.

1. A ROCK DUSTER COMPRISING A HOPPER HAVING SIDE WALLS, END WALLS AND APOROUS BOTTOM WALL, THERE BEING SPACED DISCHARGE OUTLETS IN ONE ENDWALL, A GAS CHAMBER BELOW AND COEXTENSIVE WITH THE BOTTOM WALL, MEANSFOR INTRODUCING A GASEOUS MEDIUM UNDER PRESSURE INTO SAID GAS CHAMBER, ATRANSVERSELY DISPOSED ROTARY FAN LOCATED IN FROM OF EACH DISCHARGEOUTLET, SPACED TRANSVERSE WALLS BETEEN WHICH THE FANS ARE LOCATED, THESPACE BETWEEN SAID TRANSVERSE WALLS BEING UNOBSTRUCTED ABOVE EACH FANAND AT OPPOSITE ENDS OF SAID TRANSVERSE WALLS, THERE BEING OPENINGSCONCENTRIC WITH THE FANS IN THE INNERMOST TRANSVERSE WALL, AND MEANS FORROTATING THE FANS, WHEREBY ROCK DUST WILL BE CONVEYED ALONG SAID POROUSBOTTOM WALL AND THROUGH SAID DISCHARGE OUTLETS AND DRAWN INTO SAID FANSAND WILL BE BLOWN UPWARDLY AND OUTWARDLY THEREBY FROM BETWEEN SAIDTRANSVERSE WALLS.